Wide-bandwidth antennas are desirable for a number of reasons. Firstly, they enable economies of scale in manufacture, since if an antenna can be used over a wide range of frequencies it will be applicable in more situations, so fewer different antenna designs will be required. Also, in the field of base stations for mobile telephone services, different standards are introduced from time to time, such as the UMTS standard, and these newly introduced standards do not immediately replace the existing ones, such as GSM, but have to co-exist with them. This means that base stations need to be able to operate according to more than one standard at once, and thus to operate in the different frequency bands demanded by the different standards. One possibility would be to have separate antennas for the different frequency bands, but that would add to the costs of the base stations. It would be preferable to have antennas which had a sufficiently wide bandwidth to accommodate the frequency bands of different standards.